Conveyor systems are used to move objects from one point to another, either directly or via various intermediate points. Most conveyors include a moving portion, some type of carrier for supporting an object, and a connector for connecting the carrier to the moving portion of the conveyor. Often, the carrier is spaced some distance from the moving portion of the conveyor. This arrangement allows an object on the carrier to be located at a desired elevation for processing purposes while the belts, chains and other portions of the conveyor are kept out of the way, beneath a platform or overhead, for example. This arrangement has been proven effective and is used in many diverse types of conveyor systems today.
Conveyors are often used in industrial or other environments where they are exposed to dust and dirt and airborne contaminants such as paint over-spray, chemical vapors, and water. If an object on a carrier is being exposed to paint and chemicals, the carrier will likewise be exposed. Carriers are generally relatively simple steel platforms or hooks having few moving parts and thus are not easily damaged. If they are damaged, they are relatively easy and inexpensive to replace. The rest of the conveyor system, however, including the chains, belts, switches, trolleys and trolley support tracks, can quickly be damaged when exposed to paint or chemicals or debris. This is a particular problem when the carrier is used to carry a part through a paint shop or a treatment station where chemicals are sprayed onto the part. Conveyors can also be damaged when loose parts, such as nuts or bolts, or hand tools, fall into the conveyor system. These foreign objects can cause the system to jam and/or may damage various parts of the system. Such damage is often difficult, time consuming, and expensive to fix.
One way of providing protection for the non-carrier portions of a conveyor system is to substantially enclose the conveyor track, and leave only a narrow opening above the track through which the connector or pedestal extends. This may slow down the rate at which contaminants come into contact with the conveyor system parts, but it does not eliminate, or even substantially lessen, the severity of the problem. In addition, if the opening above the track is too narrow, it may not be possible to use different pedestals with the system without extensive modifications. This construction can also make it difficult to access the conveyor mechanisms within the enclosure for maintenance and other purposes. Given the marginal improvement offered by this approach, it is often not worth the expense of installing such a system or modifying an existing system in this manner. Another approach to protecting conveyor mechanisms is to provide a two-piece cover that extends the length of the track. These cover pieces extend from either side of the track toward the track centerline and meet directly thereabove. The two cover elements fold up around the lower portion of the pedestal in the vicinity of the pedestal. This fold travels along with the pedestal as the pedestal travels down a track. Unlike the first approach outlined above, this type of seal protects all portions of a track except for those in the immediate vicinity of the pedestal.
It has been found that the two pieces of material must meet rather tightly, or even overlap, in order to form an effective seal. If the cover elements meet too tightly, however, they provide a significant degree of resistance to each passing pedestal. This problem is aggravated by the high coefficients of friction common to materials, such as various rubbers, that must be used for such covers. This drag can affect the performance of the system and may require that a more powerful drive motor be used to overcome this drag. This problem can be addressed by leaving a small space between the cover elements; however, this space allows contaminants to enter the conveyor system and will not entirely eliminate the drag. The cover elements may also bias the pedestal in a direction normal to its intended course if they push against the pedestal with unequal force, such as when they do not meet immediately above the track centerline. All of these difficulties make it undesirable to use conveyor covers of this type except when absolutely necessary, and even then, modifications to the system may be required in order to allow the system to function with these covers in place.